Stop having to sign in every time I open the MacBook.

If Require password after screen saver begins or display is turned off is grayed out, one thing to check is whether iPhone Mirroring is set to authenticate automatically. Apple says that can prevent this setting from being changed.

If you mean signing in after actually restarting or shutting down the Mac, that’s a different setting under System Settings > Users & Groups > Automatically log in as. Automatic login won’t be available if FileVault is turned on.

I’d first confirm whether you’re being asked for the password after simply opening the lid, or only after a restart. That determines which setting is involved.

For Apple laptops which include TouchID, you should consider using TouchID so you can just use your fingerprint to unlock the laptop. This will greatly minimize the number of times you will need to actually type a password, but it won't eliminate it completely. Sometimes a password is required. See the following Apple article regarding TouchID and note the information at the bottom of the article detailing times when a password will still be required:

Use Touch ID on Mac - Apple Support